Abstract
Take-all of wheat outbreaks habitually in continuous cropping fields and causes the loss of wheat crop. In Hokkaido, however, it has never occurred in the long-term continuous fields for more than 25 years. In the field of this area a ‘sterile dark mycelium’ was frequently isolated from roots of wheat. An experiment was conducted to investigate the influence of this fungus on the incidence of take-all. The incorporation of this fungus in the soil infested with Gaeumannomyces graminis var. tritici reduced the infection of takeall fungus to wheat in pot experiments. The fungus forms no spores and its identification has not yet been accomplished.
